64* INTRODUCTION. 



zoophytes, and which may also be termed with pro- 

 priety " radiated animals," (animalia radiata.) 



In the three divisions preceding this the organs 

 of motion and sensation, are symetrically disposed, 

 as it were on the two respective sides of a certain 

 axis. In this last, similar organs have a circular 

 arrangement round a common centre. The zoo- 

 phytes, in truth, approach nearly to the homogene- 

 ous character of plants. The}?" possess neither a 

 nervous system sufficiently distinct, nor particular 

 organs of sensation. In a few of them we may dis- 

 cover with difficulty, some vestiges of circulation. 

 Their resparatory organs are generally upon the 

 surface of the body. The intestines of the great 

 majority consist of a sort of bag, through which 

 there is no passage, and those which are lowest in 

 the animated series exhibit nothing but a kind 

 of homogeneous pulp possessed of motion and sen- 

 sibility*. 



* Before our author's time naturalists generally divided all in- 

 vertebrated animals into two classes, insects and worms. He com- 

 menced an attack on this division, and produced another in a me- 

 moir read to "the Society of Natural History at Paris," the 10th of 

 May, 1795, and printed in the Decade Philosophiqzie, where he ac- 

 curately distinguished the, characteristics and limits of mollusca, 

 Crustacea, insects, worms, echinodermes, and zoophytes. In a 

 memoir read to the Institute the 31st of December, 1801, he ascer- 

 tained the red-blooded worms or annelides. Finally, the Baron 

 separated these various classes into three branches, each of them 

 analagous to a branch of the vertebrata, in a paper read to the 

 .Institute in July, 1812, and afterwards printed in the Annals of the 

 Museum of Natural History, Vol. xix. 



